Sperm-inspired robots driven by magnets

By Tereza Pultarova

Published Tuesday, June 3, 2014

An international team of researchers has developed nano-robots inspired by the shape and locomotion of sperms.

The 322-micron long robots consist of a head coated in a mixture of cobalt and nickel and an uncoated tail. The robots can be set into motion when subject to oscillating magnetic fields. Even a very weak field, less than five microtesla (about the strength of a decorative refrigerator magnet), is enough to create a magnetic torque in the robot’s head that causes its tail to oscillate, propelling the robot forward.

“Nature has designed efficient tools for locomotion at micro-scales,” said Islam Khalil, a researcher at the German University of Cairo, who designed the robots, called MagnetoSperm, together with his colleague Sarthak Misra from the University of Twente.

“As technology progresses and many products get smaller, it becomes difficult to assemble objects on nano and micro scales. MagnetoSperm can be used to manipulate and assemble objects at these scales using an external source of magnetic field to control its motion.”

The researchers are then able to steer the robot by directing the magnetic field lines towards a reference point. The team believes the tiny devices could find use in a wide range of medical applications, increasing efficiency of in vitro fertilisation, drug delivery or cleaning clogged arteries.

“Our microrobots are either inspired by nature or directly use living micro-organisms such as magnetotactic bacteria and sperm cells for complex micro-manipulation and targeted therapy tasks,” said Sarthak Misra, principal investigator of the study, published in the latest issue of the Applied Physics Letters.

To create the robots, the researchers used a technique called spin-coating, applied onto a silicon support wafer. The cobalt-nickel layer was then deposited on the head using electron beam evaporation.

The researchers want to further reduce the size of the MagnetoSperm robots and are currently working on a new method to produce magnetic nanofibres that could be used as the robot’s flagellum.